Circuit breaker



March 18, 1941. R. E. BOLD cmcun: BREAKER Filed April 28, 1939 lhverrtorz Ralph E.Bold.

HIS Attorney,

Patented Mar. 18, 1941 UNITED STATES PATENT QFFICE CIRC U11 BREAKER York Applicaticn April 28, 1939, Serial No. 270,614

3 Claims.

My invention relates to circuit breakers, more particularly to oil circuit breakers of the type wherein the operating mechanism for the movable contact structure extends through apertures in the sides or top of the cover or dome of the main oil-containing tank.

Heretofore, in the operation of oil circuit breakers of the aforesaid type, oil leakage at the entrance of the operating mechanism to the breaker tank, such as at the operating crank bearings or slot-like apertures for the operating linkage, has been common particularly in the case of heavy load or short circuit current interruptions. This is due to the fact that the high pressures often generated by arcing within the breaker tend to throw oil from the tank at every crack and crevice. Since the bearings or mechanism apertures above referred to cannot for practical reasons be sealed effectively for these pressures,

some oil may escape from the tank and run down the outside walls of the breaker. This is obviously objectionable as it not only results in gradual loss of oil but also introduces a fire hazard.

In accordance with my invention this problem is efficiently solved without complicating or increasing the cost of the circuit breaker by providing a combined bearing supporting structure and oil well or pocket in the top of the breaker cover or dome. This structure depends from said cover so that the main operating crank, for example,

can be mounted in said Well and connected directly to the exterior operating mechanism through the top of said cover and to the interior movable contact structure respectively. With this arrangement, oil throw or leakage exteriorly of the oil well is effectively precluded and the excess oil that is collected in said well eventually leaks back through the bearing openings into the main tank. It will also be seen that the bearings are thus automatically lubricated by the circuit breaker oil.

My invention will be more fully set forth in the following description referring to the accompanying drawing, and the features of novelty which characterize my invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.

Referring to the drawing, Figure l is an elevational View, partly in section, of an oil circuit breaker embodying the present invention, Figure 2 is a similar illustration as viewed from one end of Figure 1, and Figure 3 is an enlarged detail view of the bearing support and oil well structure shown in Figures 1 and 2.

The oil circuit breaker shown by way of ex- (S1. Wit-15(9) ample is of a well-known three-phase type comprising an oil containing tank I, a cover or dome member 2 for the tank, insulating lead-in bushings 3 that extend through and are mounted in the cover 2, stationary contact structures 4 mounted at the lower ends of the bushings 3 within the oil tank, and a movable bridging contact 5 coacting with each pair of fixed contacts. The three bridging contacts 5 are connected through an insulating bar 5 to a double lift rod 10 5 that is operatively connected in a manner presently described to suitable operating mechanism, such as a solenoid operating mechanism I mounted exteriorly of the breaker tank. As shown, the relatively movable contact structure 15 including the bushings 3, and the operating mechanism 1 are mounted as a unit with respect to the cover or dome 2,'so that the oil tank I can be lowered in the customary manner for inspection of the contacts and routine servicing of the 20 breaker, In normal operation, the cover member 2 is tightly sealed with respect to the tank I, such as by a gasket at 2, the cover and tank being firmly bolted together as at 8 in order tightly to seal the breaker tank with respect to oil throw 25 or leakage during high current interruptions.

For the purpose of I completing the seal in a most practical manner at the point where the operating means extends through the breaker cover, there is provided a combined bearing sup- 30 port and oil well generally indicated at 9 mounted in and depending from the cover 2. Referring more particularly to Figure 3, this structure comprises a pair of spaced bearing plates ill to which is welded a heavy metal strip l l forming in effect 35 a side and lower wall of a pocket, the lateral sides of which are the bearing plates Iii. The structure 9 is mounted at one edge of the cover 2 as shown by Figure 1 directly beneath a slot or aperture l2 in the cover in registry with the upper 4 opening of the oil well, the front wall of which is formed by the side 2 of the breaker cover supporting the mechanism '1. The structure 9 is suitably secured in position as by welding at the surfaces where the cover member 2 is in contact 45 with the upper and front edges of the bearing plates l0 and wall member H respectively. It will, therefore, be apparent that the breaker housing is tightly sealed at this point except for the bearing openings at it. 50

The operating mechanism interconnecting the solenoid mechanism 11 and the movable contacts 5 within the breaker comprises in the present in stance a crank arm 13 secured to a shaft it. that is journalled in the bearing plates it. The crank arm [3 is mounted within the oil well or pocket 9 between the bearing plates l0 and extends, as illustrated by Figure 1, upward through the aperture [2 in the breaker cover to connect through a linkage at I5 to the solenoid mechanism 1. The shaft I4 extends through and beyond the bearing plates 10 at opposite sides thereof for connection with a pair of crank arms l6 that are in turn directly connected to the breaker lift rod 6 within the tank. The breaker therefore can be opened and closed in the usual manner through crank 13-45, the solenoid mechanism 1 being energized to rotate the crank clockwise to close the breaker, and a spring or the like I! being effective to open the breaker when the mechanism 1 is tripped.

In operation, such as for example during the interruption of an overload or short circuit current, the pressure developed within the breaker housing tends to force or throw oil from the housing even at very small or restricted openings. Accordingly, when some oil seeps or is forced through the bearing openings at Hi, the oil simply collects at the bottom of the well instead of running down the sides of the breaker as in previous types of breakers. It will be apparent that by reason of the depressed position of the bearings beneath the cover, there is practically no likelihood of any oil reaching the top of the breaker, even under severe operating conditions. When the oil within the well reaches the lower level of the bearing openings, it starts to seep back into the main tank so that in normal operation the oil does not reach a higher level. It will furthermore be apparent that with this arrangement the main bearing of the operating crank is automatically lubricated by the circuit breaker oil.

Although there is no necessity from the viewpoint of oil throw for covering the oil well, it

may be desirable to do so in order to prevent accumulations of dust and foreign matter in the well and to improve the general appearance of the breaker. For this purpose, a suitable detachable cover It can be mounted on the top of the breaker over the well and crank l3 as best shown by Figure 1.

Where a reciprocating instead of a rotating member is to extend through the oil well, the combination is essentially the same, and the clearance is made as small as practicable.

The oil well and bearing structure above described is obviously not limited in application to the dome-type cover disclosed. For example, it can also be applied as readily to the flat top type of breaker. Here, the fiat or plate-like top would simply be provided with an aperture or slot adjacent to one side of the breaker and the oil well structure would be mounted beneath the plate cover generally in the manner above described.

It should be understood that my invention is not limited to specific details of construction and arrangement thereof herein illustrated, and that changes and modifications may occur to one skilled in the art without departing from the spirit of my invention.

What I claim as new and desire to secure by Letters Patent of the United States, is-

1. An electric circuit breaker comprising a liquid-containing tank, a cover for said tank, movable contact structure operable within said tank, operating mechanism disposed exteriorly of said tank, and means forming a well in the top of and beneath said cover, said well being open with respect to said mechanism and closed with respect to the interior of said tank so as to prevent liquid in said well from leaking to ground, said operating mechanism and movable contact structure being interconnected by means extending through side walls of said well, liquid leaking along said interconnecting means incident to circuit interruption being entrapped in said well and subsequently returning to said tann by leakage through said well.

2. An electric circuit breaker comprising a liquid-containing tank, a cover for said tank, movable contact structure operable within said tank, operating mechanism disposed exteriorly of said tank, and means forming a pocket in the top of and beneath said cover for precluding leakage of liquid to ground, said pocket having apertures in opposite walls thereof for supporting a rotatable shaft, said shaft being disposed entirely within said tank except for the portion thereof extending through said pocket, said operating mechanism and movable contact structure being interconnected by said shaft through means disposed in said pocket whereby liquid ejected from said tank along said shaft is entrapped in said pocket, said pocket having leakage vents for returning excess liquid in said pocket to said tank.

3. An electric circuit breaker comprising a liquid-containing tank, a cover for said tank, movable contact structure operable within said tank, operating mechanism disposed exteriorly of said tank, and means forming a pocket in the top of said cover and in depending relation thereto, a crank including a shaft mounted in said pocket, said shaft extending through and being journalled in opposite walls of said pocket r for connection to said movable contact structure entirely within said tank, said crank extending from the top of said cover for connection to said operating mechanism, said pocket being positioned beneath said cover and wholly within said tank so as to entrap oil ejected from said tank along said shaft for precluding leakage to ground and means in said pocket for returning excess oil by leakage to said tank.

RALPH E. BSLD. 

